The present invention relates generally to the field of memory devices and more specifically to the field of nonvolatile memory devices containing diode steering elements.
Nonvolatile memory arrays maintain their data even when power to the device is turned off. In one-time-programmable arrays, each memory cell is formed in an initial unprogrammed state, and can be converted to a programmed state. This change is permanent, and such cells are not erasable. In other types of memories, the memory cells are erasable, and can be rewritten many times.
Cells may also vary in the number of data states each cell can achieve. A data state may be stored by altering some characteristic of the cell which can be detected, such as current flowing through the cell under a given applied voltage or the threshold voltage of a transistor within the cell. A data state is a distinct value of the cell, such as a data ‘0’ or a data ‘1’. In a one diode, one resistivity switching material memory cell, the state of the memory cell is programmed by forward biasing the diode. However, the current that surges through the diode of a memory cell when the resistivity switching material changes state during forward biasing can be difficult to control.